Author summerrain23 says: What You Need to Know About Systemic Lupus Erythematosus (SLE) What is lupus? Systemic lupus erythematosus (lupus) is a disease of the immune system. Normally, the immune system protects the body from infection. However, in lupus, the immune system inappropriately attacks tissues in various parts of the body. This abnormal activity of the immune system leads to tissue damage and illness. Who is affected by lupus? Lupus can affect men and women of any race or age. One in 2,000 people in the United States has lupus. People of African, Asian and Native American descent are more likely to develop lupus than Caucasians. If only women of child-bearing age (14 to 45 years old) are considered, as many as 1 in 250 may develop lupus. This suggests a possible role for female hormones influencing vulnerability to this disease. Feb 28, 2008